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comp.lang.ruby

Why is this DRb code so slow?

Jim Freeze

5/15/2005 3:02:00 PM

Ok, I'm stumped. I have a simple drb example, and it is
taking about 1 minute to get the value of an array with
two items in it.

% cat simple-server.rb
require 'drb'

def start_daemon
if (child_pid = fork)
File.open(__FILE__+".pid", "w") { |f| f.puts child_pid }
exit
end
Process.setsid
end

start_daemon

class MyClass
def files
%w(test1 test2)
end
end

DRb.start_service nil, MyClass.new

puts DRb.uri
File.open(__FILE__+".uri", "w") { |f| f.puts DRb.uri }
puts "Server started"
DRb.thread.join

% cat simple-client.rb
require 'drb'
DRb.start_service

server = File.read("simple-server.rb.uri").strip
puts "Connecting to #{server}"

begin
robj = DRbObject.new nil, server
p robj
p robj.object_id
p robj.files

rescue DRb::DRbConnError => err
puts "No response from server"
puts err
end

% ruby simple-server.rb
druby://cheetah.local:49506
Server started

% ruby simple-client.rb
Connecting to druby://cheetah.local:49506
#<DRb::DRbObject:0xb257c @ref=nil, @uri="druby://cheetah.local:49506">
365246
["test1", "test2"]

The last line takes about a minute to be printed.

--
Jim Freeze
Ruby: I can explain it to ya but I can't understand it fer ya.
4 Answers

Chad Fowler

5/15/2005 4:52:00 PM

0

On 5/15/05, Jim Freeze <jim@freeze.org> wrote:
> Ok, I'm stumped. I have a simple drb example, and it is
> taking about 1 minute to get the value of an array with
> two items in it.
>
> % cat simple-server.rb
> require 'drb'
>
> def start_daemon
> if (child_pid = fork)
> File.open(__FILE__+".pid", "w") { |f| f.puts child_pid }
> exit
> end
> Process.setsid
> end
>
> start_daemon
>
> class MyClass
> def files
> %w(test1 test2)
> end
> end
>
> DRb.start_service nil, MyClass.new
>
> puts DRb.uri
> File.open(__FILE__+".uri", "w") { |f| f.puts DRb.uri }
> puts "Server started"
> DRb.thread.join
>
> % cat simple-client.rb
> require 'drb'
> DRb.start_service
>
> server = File.read("simple-server.rb.uri").strip
> puts "Connecting to #{server}"
>
> begin
> robj = DRbObject.new nil, server
> p robj
> p robj.object_id
> p robj.files
>
> rescue DRb::DRbConnError => err
> puts "No response from server"
> puts err
> end
>
> % ruby simple-server.rb
> druby://cheetah.local:49506
> Server started
>
> % ruby simple-client.rb
> Connecting to druby://cheetah.local:49506
> #<DRb::DRbObject:0xb257c @ref=nil, @uri="druby://cheetah.local:49506">
> 365246
> ["test1", "test2"]
>
> The last line takes about a minute to be printed.
>

I don't know, but:

$ time ruby simple-client.rb
Connecting to druby://chad-fowlers-computer.local:51624
#<DRb::DRbObject:0x25639c
@uri="druby://chad-fowlers-computer.local:51624", @ref=nil>
1225166
["test1", "test2"]

real 0m0.215s
user 0m0.030s
sys 0m0.017s

--

Chad Fowler
http://chad...
http://rubyc...
http://ruby...
http://rubygems.rub... (over 300,000 gems served!)

Dick Davies

5/15/2005 5:45:00 PM

0

* Jim Freeze <jim@freeze.org> [0501 16:01]:
> Ok, I'm stumped. I have a simple drb example, and it is
> taking about 1 minute to get the value of an array with
> two items in it.

I'd guess DNS. check your forward and reverse for both the client
and the server.

--
'Bender, Ship, stop arguing or I'll come back there and change
your opinions manually.'
-- Leela
Rasputin :: Jack of All Trades - Master of Nuns

Jim Freeze

5/15/2005 8:15:00 PM

0

* Chad Fowler <chadfowler@gmail.com> [2005-05-16 01:51:49 +0900]:

> $ time ruby simple-client.rb
> Connecting to druby://chad-fowlers-computer.local:51624
> #<DRb::DRbObject:0x25639c
> @uri="druby://chad-fowlers-computer.local:51624", @ref=nil>
> 1225166
> ["test1", "test2"]
>
> real 0m0.215s
> user 0m0.030s
> sys 0m0.017s

Hmm, interesting. That used to work for me. It is probably DNS
related like Dick Davies mentioned, but I don't know how
to debug it yet. When I use a fixed address and port (e.g
localhost:2000), it works as yours.

--
Jim Freeze
Ruby: I can explain it to ya but I can't understand it fer ya.

Jim Freeze

5/15/2005 8:47:00 PM

0

* Dick Davies <rasputnik@hellooperator.net> [2005-05-16 02:45:29 +0900]:

> I'd guess DNS. check your forward and reverse for both the client
> and the server.

That is what I was thinking too, but then I ran it on a different
machine, and I get a no response error instead of a delayed result.

In the two cases below I use

DRb.start_service nil, obj

and

DRb.start_service dri, obj

where dri is the value originally picked by DRb itself:

"druby://rabbit:50827"

# start the server - let drb decide
% ruby drb.server
URI: 'druby://rabbit:50827'
I am server

# run the client
% ruby drb.client
#<DRb::DRbObject:0x821d804 @uri="druby://rabbit:50827", @ref=nil>
68217858
No response from server
druby://rabbit:50827 - #<Errno::ECONNREFUSED: Connection refused -
connect(2)>

# kill the old server, and manually do start_service at the previous dri:
% ruby drb.server
URI: 'druby://rabbit:50827'
I am server

% ruby drb.client
#<DRb::DRbObject:0x821d804 @uri="druby://rabbit:50827", @ref=nil>
68217858
["test1", "test2"]
# it works


So, why does the client fail if the server is running at the same
address. The only difference is that I set the address explicitly
or I let DRb choose the address.

--
Jim Freeze
Ruby: I can explain it to ya but I can't understand it fer ya.